Thursday, October 28, 2010

Crows as Clever as Great Apes, Study Says

Anyone who has watched crows, jays, ravens and other members of the corvid family will know they're anything but "birdbrained."

For instance, jays will sit on ant nests, allowing the angry insects to douse them with formic acid, a natural pesticide which helps rid the birds of parasites. Urban-living carrion crows have learned to use road traffic for cracking tough nuts. They do this at traffic light crossings, waiting patiently with human pedestrians for a red light before retrieving their prize.

Yet corvids may be even cleverer than we think. A new study suggests their cognitive abilities are a match for primates such as chimpanzees and gorillas. Furthermore, crows may provide clues to understanding human intelligence.

Published tomorrow in the journal Science, the study is co-authored by Nathan Emery and Nicola Clayton, from the departments of animal behavior and experimental psychology at Cambridge University, England.

They say that, while having very different brain structures, both crows and primates use a combination of mental tools, including imagination and the anticipation of possible future events, to solve similar problems. They base their argument on existing studies.

Emery and Clayton write, "These studies have found that some corvids are not only superior in intelligence to birds of other avian species (perhaps with the exception of some parrots), but also rival many nonhuman primates."

Increasingly, scientists agree that it isn't physical need that makes animal smart, but social necessity. Group living tends to be a complicated business, so for individuals to prosper they need to understand exactly what's going on. So highly social creatures like dolphins, chimps, and humans tend to be large-brained and intelligent.

Large Brains

The study notes that crows are also social and have unusually large brains for their size. "It is relatively the same size as the chimpanzee brain," the authors said.

They say that crows and apes both think about their social and physical surroundings in complex ways, using tool use as an example.

Like apes, many birds employ tools to gather food, but it isn't clear whether chimps or crows appreciate how these tools work. It may be that they simply discover their usefulness by accident. However, studies of New Caledonian crows, from the South Pacific, suggest otherwise.